docs: def filter(self, record):
          """Is the specified record to be logged? Returns zero for no,
          nonzero for yes. If deemed appropriate, the record may be modified
          in-place by this method.
  
          :param logging.LogRecord record: The log record to process
          :rtype: int
  
          """
          if self._exists:
              return int(getattr(record, 'correlation_id', None) is not None)
          return int(getattr(record, 'correlation_id', None) is None)